"We hold that: (1) Quaid did not infringe Vault's exclusive right to reproduce its program in copies under § 106(1); (2) Quaid's advertisement and sale of RAMKEY does not constitute contributory infringement; (3) RAMKEY does not constitute a derivative work of Vault's program under § 106(2); and (4) the provision in Vault's license agreement, which prohibits the decompilation or disassembly of its program, is unenforceable."
in https://cyber.harvard.edu/ilaw/Contract/vault.htm
Edit: there is a Wikipedia page for that https://en.wikipedia.org/wiki/Vault_Corp._v._Quaid_Software_.... (there is a dot at the end of the URL but HN parser does not treat it correctly)
I played the modern version (Leisure Suit Larry Reloaded) a bit but couldn't complete the age verification because it relied on the American history and pop culture too much. Had to shamefully google the answers.
(Bearing in mind that photocopiers were uncommon at the time.)
In the case of Leisure Suit Larry the opening questions were actually designed as an age-test. The intention was that "children" wouldn't know the answers and would be unable to play the "risqué" game.
https://en.wikipedia.org/wiki/Leisure_Suit_Larry_in_the_Land...
Having been a kid during the formative years of the Internet, I can tell you that the notion of "you can find everything on the internet" doesn't really start coming into play until the early 2000s. In the late 90s, having to do research generally meant schlepping yourself to the library and finding encyclopedias or other research materials. Or, if you were lucky, maybe you had something like Microsoft Encarta, an encyclopedia on a CD-ROM!
That was a bit later, though. In the age of physical disk swapping, you would ask friends, or prepare for an audience with That One Guy Who Has Everything And Knows Everything.
The solution was to just get an updated version of copy2pc or copywrite and they would have a fix.
But I remember a few schemes that were interesting workarounds.
One was the hole in the disk, one was a laser-burned dot on the disk.
I recall with the hole in the disk - the software would try to read and if it succeeded it was a copy.
The second one was slightly different and I believe the software would write to it, and read it back, and if it could read it back it was a copy.
However the best of all was either the scratch-n-sniff card from Leather Godesses of Phobos, or the Age Verification of Leisure Suit Larry.
example:
or